Projectors display images by modulating light from an illumination optical system in response to image information (image signal) by means of a liquid crystal panel, and projecting the modulated light onto a screen.
A liquid crystal light valve is typically composed of a liquid crystal panel, and a polarizing plate provided to the light incident side and/or light exiting side thereof The polarizing plate allows transmission of only the component of light in the direction of the polarization axis, and blocks other components of light. Where a polarizing plate includes organic material, the polarizing plate absorbs light other than the light component in the direction of the polarization axis, and thus generates heat. If due to this heat generation the temperature of the polarizing plate rises, distortion and deterioration of the polarizing plate may occur, and optical characteristics may drop. Specifically, the polarizing plate allows transmission of the light component that should not pass through, and blocks the light component that should not be blocked. For this reason, in the past, a cooling fan was used to actively cool the liquid crystal light valve including the polarizing plate.
However, when miniaturizing a projector, it may be difficult to install a cooling fan, or it will be necessary to miniaturize the cooling fan. In such cases, there has been the problem that the polarizing plate cannot be cooled adequately, and the temperature rise of the polarizing plate becomes relatively large.
This problem is common to any optical elements including organic material for controlling the polarization state of light exiting from the optical elements (hereinafter also termed “polarization control elements”).